Magnetic recording on bit patterned media (BPM) is seen as a way to increase the areal recording density compared to conventional magnetic recording while avoiding the problem of the super-paramagnetic limit. The surface of the recording medium includes an array of islands and trenches. Different geometries are possible for the bit island locations including the staggered geometry.
In bit patterned media, the magnetic material on a disc is patterned into small isolated blocks or islands such that there is a single magnetic domain in each island or “bit”. The single magnetic domains can be a single grain or a plurality of strongly coupled grains that switch magnetic states in concert as a single magnetic volume. This is in contrast to continuous media wherein a single “bit” may have multiple magnetic domains separated by domain walls. The media may be fabricated so that there is no magnetic material in the regions between the blocks.
In magnetic recording systems that use continuous media, there is no need to synchronize the writing of the data with the position of the media. For this reason, the data is written using a free running clock and sampling instances are recovered during the read process. However, for bit patterned media, the locations of the bits to be written are predefined (i.e., on the bit islands), and write synchronization is needed.